Thermally assisted magnetic head, head gimbal assembly, and hard disk drive

ABSTRACT

A slider has a slider substrate, an electromagnetic transducer, a waveguide for receiving light from a surface on the side opposite from a medium-opposing surface and guiding the light to the medium-opposing surface side, and a device electrode electrically connected to the electromagnetic transducer. A light source unit includes a light source supporting substrate, a light source, and a lead extending from the slider side to the side opposite from the slider and having both end parts exposed at a surface of the light source unit. The device electrode of the slider is exposed at the surface of the slider on the side opposite from the medium-opposing surface without being covered with the light source unit. An end part on the slider side of the lead of the light source unit is soldered to the device electrode of the slider.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thermally assisted magnetic headwhich writes signals by a thermally assisted magnetic recording scheme,a head gimbal assembly (HGA) equipped with the thermally assistedmagnetic head, and a hard disk drive equipped with the HGA.

2. Related Background Art

As hard disk drives have been increasing their recording density,thin-film magnetic heads have been required to further improve theirperformances. As the thin-film magnetic heads, those of composite typehaving a structure in which a magnetism detecting device such asmagnetoresistive (MR) device and an electromagnetic transducer such aselectromagnetic coil device are laminated have been in wide use, whilethese devices read/write data signals from/onto magnetic disks which aremagnetic recording media.

In general, a magnetic recording medium is a sort of discontinuous bodyin which magnetic fine particles are assembled, while each magnetic fineparticle has a single-domain structure. Here, one recording bit isconstituted by a plurality of magnetic fine particles. Therefore, forenhancing the recording density, it is necessary to make the magneticfine particles smaller, so as to reduce irregularities at boundaries ofrecording bits. When the magnetic fine particles are made smaller,however, their volume decreases, so that the thermal stability inmagnetization may deteriorate, thereby causing a problem.

An index of the thermal stability in magnetization is given byK_(U)V/k_(B)T. Here, K_(U) is the magnetic anisotropy energy, V is thevolume of one magnetic fine particle, k_(B) is the Boltzmann constant,and T is the absolute temperature. Making the magnetic fine particlessmaller just reduces V, thereby lowering K_(U)V/k_(B)T by itself, whichworsens the thermal stability. Though K_(U) may be made greater at thesame time as measures against this problem, the increase in K_(U)enhances the coercivity of the recording medium. On the other hand, thewriting magnetic field intensity caused by a magnetic head issubstantially determined by the saturated magnetic flux density of asoft magnetic material constituting a magnetic pole within the head.Therefore, no writing can be made if the coercivity exceeds apermissible value determined by the limit of writing magnetic fieldintensity.

Proposed as a method for solving such a problem in thermal stability ofmagnetization is a so-called thermally assisted magnetic recordingscheme which imparts heat to a part of a recording medium by irradiationwith light from a light source at the time of applying a writingmagnetic field, while using a magnetic material having a large value ofK_(U), so as to effect writing with lowered coercivity by a magneticrecording device (see, for example, Japanese Patent ApplicationLaid-Open No. 10-162444, No. 2001-255254, No. 2004-158067, No.2006-185548, IEEE Trans. Magn. Vol. 41, No. 10 pp. 2817-2821 (2005))

SUMMARY OF THE INVENTION

Meanwhile, FIG. 8 of Patent Document 1 and the like disclose a mode inwhich a supporting substrate for a laser diode is arranged on the rearface of a slider, while light from the laser diode secured to thesupporting substrate is guided toward a recording medium through awaveguide provided in the slider. In such a mode, electric connection ishard to achieve between an electromagnetic transducer or magneticreading device in the slider and an electrode provided in a suspension.

For example, the slider may be provided with respective electrodeselectrically connected to the electromagnetic transducer and magneticreading device, and these electrodes may be connected to electrodes inthe suspension with bonding wires. As the number of bonding wires isgreater, however, the wires are more likely to come into contact withother objects during their assembling process and cause failures.Therefore, it will be preferred if the number of bonding wires isreduced.

In view of such a problem, it is an object of the present invention toprovide a thermally assisted magnetic head with a favorable yield, anHGA equipped with this thermally assisted magnetic head, and a hard diskdrive equipped with this HGA.

In one aspect, the present invention provides a thermally assistedmagnetic head comprising a slider having a medium-opposing surface, anda light source unit arranged on a surface of the slider on the sideopposite from the medium-opposing surface. The slider has a slidersubstrate, an electromagnetic transducer, a waveguide for receivinglight from the surface opposite from the medium-opposing surface andguiding the light to the medium-opposing surface side, and a deviceelectrode electrically connected to the electromagnetic transducer. Thelight source unit has a light source supporting substrate secured withrespect to the slider substrate, a light source secured with respect tothe light source supporting substrate so as to be able to supply thelight to the waveguide, and a lead extending from the slider side to theside opposite from the slider and having both end parts exposed at asurface of the light source unit. The device electrode of the slider isexposed at the surface of the slider on the side opposite from themedium-opposing surface without being covered with the light sourceunit, or exposed at a side face of the medium-opposing surface of theslider. An end part on the slider side of the lead of the light sourceunit is soldered to the device electrode of the slider.

In another aspect, the present invention provides a thermally assistedmagnetic head having the same structure as that of the above-mentionedthermally assisted magnetic head except that the slider has a slidersubstrate, an electromagnetic transducer, an auxiliary device to beapplied with a voltage, a waveguide for receiving light from the surfaceopposite from the medium-opposing surface and guiding the light to themedium-opposing surface side, and a device electrode electricallyconnected to the auxiliary device.

According to these aspects of the present invention, the deviceelectrode for supplying electricity to the device of the slider canelectrically be connected to an electrode in a suspension through thesolder and the lead of the light source unit without bonding wires. Thiscan reduce failures caused by the bonding wires.

Preferably, both end parts of the lead of the light source unit areexposed at the same side face of the light source unit, while the deviceelectrode of the slider is exposed at the surface of the slider on theside opposite from the medium-opposing surface without being coveredwith the light source unit.

This makes it easy to solder the electrode of the suspension to the leadof the light source unit, and the lead of the light source unit to thedevice electrode of the slider.

Preferably, the light source and lead are arranged on the same side faceof the light source supporting substrate, an intermediate part of thelead between the end part on the slider side and the end part on theside opposite from the slider is covered with an insulating layerwithout being exposed at the surface of the light source unit, a lightsource electrode is provided on the insulating layer, and the lightsource is arranged on the light source electrode.

This is easy to manufacture, since the light source, lead, and lightsource electrode are formed on the same side face of the light sourcesupporting substrate. Since the light source electrode overpasses thelead while being electrically insulated therefrom, the width and lengthof the light source electrode can be made greater while effectivelyutilizing the area of one side face of the light source supportingsubstrate. This makes it easy to electrically connect the light sourceand the light source electrode to each other and form the light sourceelectrode with a part not covered with the light source, and a lightemission test for the light source and the like can favorably beperformed while using this uncovered part.

The head gimbal assembly in accordance with the present inventioncomprises the above-mentioned thermally assisted magnetic head and asuspension for supporting the thermally assisted magnetic head.

The hard disk drive in accordance with the present invention comprisesthe above-mentioned head gimbal assembly and a magnetic recordingmedium.

The present invention can provide a thermally assisted magnetic headwith a favorable yield, an HGA equipped with this thermally assistedmagnetic head, and a hard disk drive equipped with this HGA.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the hard disk drive in accordance with afirst embodiment;

FIG. 2 is a perspective view of an HGA 17;

FIG. 3 is an enlarged perspective view of a thermally assisted magnetichead 21 shown in FIG. 1 and its vicinity;

FIG. 4 is a plan view of a main part of the magnetic head as seen fromthe medium-opposing surface side;

FIG. 5 is a sectional view of the thermally assisted magnetic head 21taken along the line V-V of FIG. 3;

FIG. 6 is a sectional view of the thermally assisted magnetic head 21taken along the line VI-VI of FIG. 3;

FIG. 7 is a perspective view of a laser diode 40; and

FIG. 8 is a perspective view of the hard disk drive in accordance withthe first embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, modes for carrying out the present invention will beexplained in detail with reference to the drawings. In the drawings, thesame constituents are referred to with the same numerals or letters. Foreasier viewing of the drawings, ratios of dimensions within and amongthe constituents in the drawings are arbitrary.

First Embodiment

Hard Disk Drive

FIG. 1 is a perspective view of the hard disk drive in accordance withan embodiment.

The hard disk drive 1 comprises a plurality of magnetic disks 10 whichare magnetic recording media rotating about a rotary shaft of a spindlemotor 11, an assembly carriage apparatus 12 for positioning thermallyassisted magnetic heads 21 onto tracks, and a read/write control circuit13 for controlling writing and reading actions by the thermally assistedmagnetic heads 21 and regulating a laser diode 40 which is a lightsource for generating laser light for thermally assisted magneticrecording as will be explained later in detail.

The assembly carriage apparatus 12 is provided with a plurality ofdriving arms 14. These driving arms 14 can be swung about a pivotbearing shaft 16 by a voice coil motor (VCM) 15, and are laminated in adirection along the pivot bearing shaft 16. A head gimbal assembly (HGA)17 is attached to a leading end part of each driving arm 14. Each HGA 17is provided with the thermally assisted magnetic head 21 opposing thefront face of its corresponding magnetic disk 10. In the thermallyassisted magnetic head 21, the surface opposing the front face of themagnetic disk 10 is the medium-opposing surface (also known as airbearing surface) S. The magnetic disk 10, driving arm 14. HGA 17, andthermally assisted magnetic head 21 may be provided singly as well.

HGA

FIG. 2 is a perspective view of the HGA 17. This drawing shows the HGA17 with its medium-opposing surface S facing up.

The HGA 17 is constructed by firmly attaching the thermally assistedmagnetic head 21 to a leading end part of a suspension 20 andelectrically connecting one end of a wiring member 203 to a terminalelectrode of the thermally assisted magnetic head 21. The suspension 20is mainly constituted by a load beam 200, an elastic flexure 201 firmlyattached onto and supported by the load beam 200, a tongue 204 formedlike a leaf spring at the leading end of the flexure 201, a base plate202 provided at a base part of the load beam 200, and a wiring member203 which is formed on the flexure 201 and comprises lead conductors andconnecting pads electrically connected to both ends of the leadconductors.

It is clear that the suspension in the HGA 17 is not limited to thestructure mentioned above. Though not depicted, an IC chip for drivingthe head may be mounted somewhere in the suspension 20.

Thermally Assisted Magnetic Head

FIG. 3 is an enlarged perspective view of the thermally assistedmagnetic head 21 shown in FIG. 1 and its vicinity. FIG. 4 is a view of amain part of the thermally assisted magnetic head 21 in FIG. 3 as seenfrom the medium-opposing surface S. FIG. 5 is a sectional view of thethermally assisted magnetic head 21 taken along the line V-V of FIG. 3FIG. 6 is a sectional view of the thermally assisted magnetic head 21taken along the line VI-VI of FIG. 3.

The thermally assisted magnetic head 21 has a structure in which a lightsource unit 23 comprising a light source supporting substrate 230 and alaser diode 40 to become a light source for thermally assisted magneticrecording, and a slider 22 having a slider substrate 220 and a magnetichead part 32 are bonded and secured to each other such that a back face2201 of a slider substrate 220 and a bonding surface 2300 of the lightsource supporting substrate 230 are in contact with each other. The backface 2201 of the slider substrate 220 is a surface of the slider 22 onthe side opposite from the medium-opposing surface S. The bottom face2301 of the light source supporting substrate 230 is bonded to thetongue 204 of the flexure 201 by an adhesive 45 such as epoxy resin, forexample (see FIGS. 5 and 6).

The slider 22 comprises the slider substrate 220 and a magnetic headpart 32 for writing and reading data signals.

The slider substrate 220 exhibits a planar form and has themedium-opposing surface S processed such as to yield an appropriateflying height (not depicted). The slider substrate 220 is formed byAlTiC (Al₂O₃—TiC) or the like which is conductive.

As shown in FIGS. 3 to 5, the magnetic head part 32 is formed on anintegration surface 2202 which is a side face substantiallyperpendicular to the medium-opposing surface S of the slider substrate220. The magnetic head part 32 comprises an MR device 33 as a magnetismdetecting device for detecting magnetic information, an electromagneticcoil device 34 as a perpendicular (or in-plane) magnetic recordingdevice for writing magnetic information by generating a magnetic field,a waveguide 35 as a planar waveguide provided between the MR device (anauxiliary device to be applied with a voltage) 33 and electromagneticcoil device 34, a near-field-light-generating part (also referred to asplasmon probe) 36 for generating near-field light for heating therecording layer part of the magnetic disk, and an insulating layer 38functioning as a cladding formed on the integration surface 2202 so asto cover the MR device 33, electromagnetic coil device 34, waveguide 35,and near-field-light-generating part 36.

As shown in FIG. 3, the magnetic head part 32 further comprises deviceelectrodes 371, 372, 373, 374, 375, 376 formed so as to be exposed at asurface 32 a of the magnetic head part 32 on the side opposite from themedium-opposing surface S. The device electrodes 371, 372 areelectrically connected to respective input terminals of the MR device33. The device electrodes 373, 374 are electrically connected to inputterminals of the electromagnetic coil device 34, more specifically toboth ends of the coil, respectively. The device electrodes 375, 376 areused for setting the slider substrate 220 to the ground potential, orfor an undepicted heater (an auxiliary device to be applied with avoltage) provided within the slider. For setting the slider substrate220 to the ground potential, it will be sufficient if the deviceelectrode 375 is electrically connected to the slider substrate 220through a via hole or the like, though not illustrated.

Here, the light source unit 23 is arranged so as to expose the deviceelectrodes 371 to 376 and waveguide 35 at the surface 32 a of themagnetic head part 32 in the slider 22, i.e., so as not to totally coverthe device electrodes 371 to 376.

As shown in FIGS. 4 and 5, the MR device 33, electromagnetic coil device34, and near-field-light-generating part 36 have respective end facesexposed at the medium-opposing surface S.

As shown in FIG. 5, the MR device 33 includes an MR multilayer body 332,and a lower shield layer 330 and an upper shield layer 334 which arearranged at positions holding the MR multilayer body 332 therebetween.Each of the lower and upper shield layers 330, 334 can be constituted bya magnetic material such as NiFe, CoFeNi, CoFe, FeN, or FeZrN having athickness of about 0.5 to 3 μm formed by pattern plating such as frameplating or the like, for example. The lower and upper shield layers 330,334 prevent the MR multilayer body 332 from being affected by externalmagnetic fields which become noise.

The MR multilayer body 332 includes a magnetoresistive film such as CIP(Current In Plane) GMR (Giant Magneto Resistive) multilayer film, CPP(Current Perpendicular to Plane) GMR multilayer film, or TMR (TunnelingMagneto Resistive) multilayer film, and senses signal magnetic fieldsfrom magnetic disks with a very high sensitivity.

When including a TMR multilayer film, for example, the MR multilayerbody 332 has a structure in which an antiferromagnetic layer having athickness of about 5 to 15 nm made of IrMn, PtMn, NiMn, RuRhMn, or thelike, a magnetization fixed layer which is constituted by aferromagnetic material such as CoFe or two layers of CoFe or the likeholding a nonmagnetic metal layer such as Ru therebetween, for example,and has a direction of magnetization fixed by the antiferromagneticlayer, a tunnel barrier layer made of a nonmagnetic dielectric materialformed by oxidizing a metal film having a thickness of about 0.5 to 1 nmmade of Al, AlCu, or the like by oxygen introduced into a vacuumapparatus or naturally, for example, and a free magnetization layerwhich is constituted by a two-layer film constituted by CoFe or the likehaving a thickness of about 1 nm and NiFe or the like having a thicknessof about 3 to 4 nm which are ferromagnetic materials, for example, andforms tunneling exchange coupling with the magnetization fixed layerthrough the tunnel barrier layer are successively laminated.

An interdevice shield layer 148 made of a material similar to that ofthe lower shield layer 330 is formed between the M device 33 andwaveguide 35. The interdevice shield layer 148 acts to shield the MRdevice 33 from magnetic fields generated by the electromagnetic coildevice 34, so as to prevent exogenous noise from occurring at the timeof reading.

The insulating layer 38 made of alumina or the like is formed betweenthe shield layers 330, 334 on the side of the M multilayer body 332opposite from the medium-opposing surface S, on the side of the shieldlayers 330, 334, 148 opposite from the medium-opposing surface S,between the lower shield layer 330 and slider substrate 220, and betweenthe interdevice shield layer 148 and optical waveguide 35.

When the M multilayer body 332 includes a CIP-GMR multilayer film, upperand lower shield gap layers for insulation formed from alumina or thelike are provided between the MR multilayer body 332 and the upper andlower shield layers 334, 330, respectively. Though not depicted, an MRlead conductor layer for supplying a sense current to the MR multilayerbody 332 and taking out its reproduced output is also provided. When theM multilayer body 332 includes a CPP-GMR multilayer film or TMRmultilayer film, on the other hand, the upper and lower shield layers334, 330 also fanction as upper and lower electrode layers,respectively. In this case, the upper and lower shield gap layers and MRlead conductor layer are unnecessary and omitted.

Formed on both sides in the track width direction of the MR multilayerbody 332 is a hard bias layer (not depicted) made of a ferromagneticmaterial such as CoTa, CoCrPt, or CoPt for applying a longitudinal biasmagnetic field for stabilizing magnetic domains.

The electromagnetic coil device 34 is preferably one used forperpendicular magnetic recording and comprises, as shown in FIG. 5, amain magnetic pole layer 340, a gap layer 341 a, a coil insulating layer341 b, a coil layer 342, and an auxiliary magnetic pole layer 344.

The main magnetic pole layer 340 is a magnetic waveguide by which amagnetic flux induced by the thin-film coil 342 is guided to therecording layer of the magnetic disk (medium) to be written while beingconverged. Here, the end part of the main magnetic pole layer 340 on themedium-opposing surface S side is preferably made smaller than the otherpart in terms of the width in the track width direction (the sheet depthdirection of FIG. 5) and the thickness in the laminating direction (thehorizontal direction of FIG. 5). As a result, a fine, strong writingmagnetic field adapted to higher recording density can be generated.

The end part on the medium-opposing surface S side of the auxiliarymagnetic pole layer 344 magnetically connected to the main magnetic polelayer 340 forms a trailing shield part having a layer cross sectionlarger than that of the other part of the auxiliary magnetic pole layer344. The auxiliary magnetic pole layer 344 opposes the end part of themain magnetic pole layer 340 on the medium-opposing surface S sidethrough the gap layer (cladding) 341 a and coil insulating layer 341 bmade of an insulating material such as alumina.

The auxiliary magnetic pole layer 344 is constituted by an alloy made oftwo or three elements among Ni, Fe, and Co, an alloy mainly composed ofthem and doped with a predetermined element, or the like having athickness of about 0.5 to 5 μm, for example, formed by frame plating,sputtering, or the like, for example.

The gap layer 341 a, which separates the coil layer 342 and mainmagnetic pole layer 340 from each other, is constituted by Al₂O₃, DLC,or the like having a thickness of about 0.01 to 0.5 μm, for example,formed by sputtering, CVD, or the like, for example.

The coil layer 342 is constituted by Cu or the like having a thicknessof about 0.5 to 3 μm, for example, formed by frame plating or the like,for example. The rear end of the main magnetic pole layer 340 and thepart of the auxiliary magnetic pole layer 344 remote from themedium-opposing surface S are joined together, while the coil layer 342is formed so as to surround this joint.

The coil insulating layer 341 b separates the coil layer 342 andauxiliary magnetic pole layer 344 from each other and is constituted byan electrically insulating material such as thermally cured alumina orresist layer having a thickness of about 0.1 to 5 μm, for example.

As shown in FIG. 4, the leading end of the magnetic pole end part 340 onthe medium-opposing surface S side is tapered such as to form aninverted trapezoid in which a side on the leading side, i.e., the slidersubstrate 220 side, is shorter than a side on the trailing side.

The end face of the magnetic pole end part 340 on the medium-opposingsurface side is provided with a bevel angle θ so as not to causeunnecessary writing and the like in adjacent tracks under the influenceof skew angles generated when driven by a rotary actuator. The bevelangle θ is about 15°, for example. In practice, the writing magneticfield is mainly generated near the longer side on the trailing side,while the length of the longer side determines the width of a writingtrack in the case of magnetic dominant recording.

Here, the main magnetic pole layer 340 is preferably constituted by analloy made of two or three elements among Ni, Fe, and Co, an alloymainly composed of them and doped with a predetermined element, or thelike having a total thickness of about 0.01 to 0.5 μm at the end part onthe medium-opposing surface S side and a total thickness of about 0.5 to3.0 μm except for the end part, for example, formed by frame plating,sputtering, or the like, for example. The track width can be set toabout 100 nm, for example.

As shown in FIG. 5, the optical waveguide 35, which is shaped like arectangular plate in this embodiment, is positioned between the MRdevice 33 and electromagnetic coil device 34, and extends parallel tothe integration surface 2202 from the medium-opposing surface S of themagnetic head part 32 to the surface 32 a of the magnetic head part 32on the side opposite from the medium-opposing surface S. In thewaveguide 35, as shown in FIG. 4, two side faces 351 a, 351 b opposingeach other in the track width direction and two side faces 352 a, 352 bparallel to the integration surface 2202 are in contact with theinsulating layer 38 having a refractive index smaller than that of thewaveguide 35 and functioning as a cladding for the waveguide 35 actingas a core.

Returning to FIG. 5 and letting X, Y, and Z axes be the thickness,width, and longitudinal directions of the waveguide 35, respectively,the light emitted along the Z axis from the light-emitting surface ofthe laser diode 40 is incident on a light entrance surface 354. Thewaveguide 35 can guide the light incident on the light entrance surface354 to a light exit surface 353, which is the end face on themedium-opposing surface S side, while reflecting the light by its sidefaces. The width W35 in the track width direction and thickness T35 ofthe waveguide 35 shown in FIG. 4 can be set to 1 to 200 μm and 2 to 10μm, respectively, for example, while the height H35 shown in FIG. 5 canbe set to 10 to 300 μm, for example.

The waveguide 35 is constituted by a dielectric material, formed bysputtering, for example, thoroughly having a refractive index n higherthan that of the material forming the insulating layer 38. When theinsulating layer 38 as a cladding is formed by SiO₂ (n=1.5), forexample, the waveguide 35 may be formed by Al₂O₃ (n=1.63). When theinsulating layer 38 is formed by Al₂O₃ (n=1.63), the waveguide 35 may beformed by Ta₂O₅ (n=2.16), Nb₂O₅ (n=2.33), TiO (n=2.3 to 2.55), or TiO₂(n=2.3 to 2.55). When the waveguide 35 is constituted by such amaterial, the propagation loss of laser light is reduced not only byfavorable optical characteristics inherent in the material but also bythe fact that the total reflection condition is attained at theinterface, whereby the efficiency by which the near-field light occursimproves.

As shown in FIGS. 4 and 5, the near-field-light-generating part 36 is aplanar member arranged at the light exit surface 353 of the waveguide35. As shown in FIG. 5, the near-field-light-generating part 36 isburied in the light exit surface 353 of the waveguide 35 so as to exposean end face at the medium-opposing surface S. As shown in FIG. 4, thenear-field-light-generating part 36 exhibits a triangular form as seenfrom the medium-opposing surface S side and is formed by a conductivematerial. Examples of the conductive material include metals such as Auand alloys.

A base 36 d of the triangle is arranged parallel to the integrationsurface 2202 of the slider substrate 220, i.e., parallel to the trackwidth direction, while a pointed end part 36 c opposing the base 36 d isarranged closer to the main magnetic pole layer 340 than is the base 36d. Specifically, the pointed end part 36 c is arranged so as to opposethe leading edge of the main magnetic pole layer 340. A preferable formof the near-field-light-generating part 36 is an isosceles triangle inwhich two base angles at both ends of the base 36 d are equal.

The height H36 of the triangle of the near-field-light-generating part36 is sufficiently smaller than the wavelength of the incident laserlight, preferably 20 to 400 nm. The width W36 of the base 36 d issufficiently smaller than the wavelength of the incident laser light,preferably 20 to 400 nm. The angle at the vertex yielding the pointedend 36 c is 60 degrees, for example.

The thickness of the near-field-light-generating part 36 is preferably10 to 100 nm. Such waveguide 35, near-field-light-generating part 36,and the like can easily be formed by photolithography techniques such asliftoff.

When the near-field-light-generating part 36 is irradiated with thelight from the laser diode 40, near-field light is mainly generated bythe pointed end part 36 c. This seems to be because, when thenear-field-light-generating part 36 is irradiated with light, electronsin the metal constituting the near-field-light-generating part 36 aresubjected to plasma oscillations, so that electric fields are convergedat its leading end part.

Though depending on the wavelength of incident laser light and the formof the waveguide 35, the near-field light generated by thenear-field-light-generating part 36 has the highest intensity at theboundary of the near-field-light-generating part 36 as seen from themedium-opposing surface S in general. In this embodiment in particular,the electric field vector of light reaching thenear-field-light-generating part 36 lies in the laminating direction (Xdirection) of the laser diode 40. Therefore, the strongest radiation ofnear-field light occurs in the vicinity of the leading end 36 c. Namely,in a thermally assisted action in which the recording layer part of themagnetic disk is heated by light, the part opposing the vicinity of theleading end 36 c becomes a major heating action part.

The electric field intensity of the near-field light is incomparablystronger than that of incident light, while this very strong near-fieldlight rapidly heats an opposing local part of the magnetic disk surface.Consequently, the coercivity of this local part decreases to such alevel as to enable writing by the writing magnetic field. Therefore,writing by the electromagnetic coil device 34 is allowed even when usinga magnetic disk having a high coercivity for high-density recording. Thenear-field light reaches a depth of about 10 to 30 nm from themedium-opposing surface S toward the surface of the magnetic disk.Hence, at the current flying height of 10 nm or less, the near-fieldlight can sufficiently reach the recording layer part. Thus generatednear-field light has a width in the track width direction or mediummoving direction on a par with the depth reached thereby, while itselectric field intensity exponentially decays as it travels farther, andtherefore can heat the recording layer part of the magnetic disk verylocally. In the case of optical dominant recording, the diameter ofnear-field light determines the writing track width.

The form of the near-field-light-generating part 36 can be modified invarious ways without being restricted to the one mentioned above.

Light Source Unit

Constituents of the light source unit 23 in the thermally assistedmagnetic head 21 will now be explained with reference to FIGS. 3 to 6.

The light source unit 23 mainly comprises the light source supportingsubstrate 230, the laser diode (light source) 40 having a planar outerform, leads 471, 472, 473, 474, 475, 476, and light source electrodes47, 48.

The light source supporting substrate 230 is a substrate made of AlTiC(Al₂O₃—TiC) or the like and has the bonding surface 2300 bonded to theback face 2201 of the slider substrate 220 as shown in FIG. 5. A heatinsulating layer 230 a made of alumina or the like is formed on thebonding surface 2300. An insulating layer 41 formed from an insulatingmaterial is provided on a device forming surface 2302 which is one sideface when the bonding surface 2300 is taken as the bottom face. As shownin FIG. 3, the light source electrodes 47, 48 are formed on theinsulating layer 41, while the laser diode 40 is secured onto the lightsource electrode 47. The leads 471 to 476 are provided in the insulatinglayer 41.

The material for the insulating layer 41 is not restricted inparticular, but preferably an electrically insulating material having ahigh thermal conductivity, examples of which include AlN, diamond-likecarbon, and SiC. Though not restricted in particular, the thickness ofthe insulating layer 41 is preferably 0.1 to 100 μm, for example.

As shown in FIG. 3, the leads 471 to 476 are buried within theinsulating layer 41. The leads 471 to 476 extend in a directionperpendicular to the medium-opposing surface S, i.e., in the thicknessdirection of the light source unit 23. On the slider 22 side, the leads471 to 476 have respective end parts 471 a to 476 a exposed at a surface411 of the insulating layer 41 forming a side face of the light sourceunit 23. On the side opposite from the slider 22, the leads 471 to 476have respective end parts 471 b to 476 b exposed at the surface 411 ofthe insulating layer 41. On the other hand, intermediate parts 471 c to476 c which are positioned between the end parts 471 a to 476 a on theslider 22 side and the end parts 471 b to 476 b on the side oppositefrom the slider 22 are covered with the insulating layer 41 and notexposed at the surface 411.

Such leads can be manufactured by photolithography, plating, or the likewith a metal such as Au or Cu, for example.

As shown in FIGS. 3 and 6, the device electrodes 371 to 376 of theslider 22 are electrically connected to the end parts 471 a to 476 a onthe slider 22 side of the leads 471 to 476 in the light source unit 23,respectively, through reflowed solder pieces 250.

As shown in FIG. 3, a pair of leads constituting the wiring member 203are electrically connected to the electrodes 273, 274 of the suspension20, while the electrodes 273, 274 are electrically connected to the endparts 473 b, 474 b of the leads 473, 474 on the side remote from theslider 22 through reflowed solder pieces 252, respectively, whereby avoltage can be applied to both ends of the electromagnetic coil device34 (see FIG. 4 and the like). When a voltage is applied between a pairof device electrodes 371, the electromagnetic coil device 34 as anelectromagnetic transducer is energized, whereby a writing magneticfield occurs.

Another pair of leads constituting the wiring member 203 areelectrically connected to the electrodes 271, 272 of the suspension 20,while the electrodes 271, 272 are electrically connected to the endparts 471 b, 472 b of the leads 471, 472 on the side remote from theslider 22 through reflowed solder pieces 252, respectively, whereby avoltage can be applied to both ends of the M device 33 (see FIG. 4).When a voltage is applied between a pair of electrodes 271, 272, a sensecurrent flows through the MR device 33. Information written in therecording medium can be read by causing the sense current to flowthrough the MR device 33.

Still another pair of leads constituting the wiring member 203 areelectrically connected to the electrodes 275, 276 of the suspension 20,while the electrodes 275, 276 are electrically connected to the endparts 475 b, 476 b of the leads 475, 476 on the side remote from theslider 22 through reflowed solder pieces 252, respectively, whereby avoltage can be applied to a heater or the like in the insulating layerif any, for example. Also, the potential of one of them can be used toground the slider substrate 220 of the slider 22.

As shown in FIG. 3, the light source electrode 47 is formed at thecenter part of the surface 411 of the insulating layer 41 so as toextend in the track width direction. Here, the light source electrode 47is arranged so as to pass above the intermediate parts 473 c, 474 c, 476c of the leads 473, 474, 476, while interposing the insulating layer 41therebetween, and overpasses them. On the other hand, the light sourceelectrode 48 is formed at a position separated in the track widthdirection from the light source electrode 47. The light source electrode48 is arranged so as to pass above the intermediate parts 471 c, 472 c,475 c of the leads 471, 472, 475, while interposing the insulating layer41 therebetween, and overpasses them. The light source electrodes 47, 48further extend toward the flexure 201 for connection with the flexure201 by solder reflow.

As shown in FIG. 5, the light source electrode 47 is electricallyconnected to the light source supporting substrate 230 through a viahole 47 a provided within the insulating layer 41. The light sourceelectrode 47 also functions as a heat sink for transferring heatoccurring at the time of driving the laser diode 40 toward the lightsource supporting substrate 230 through the via hole 47 a. Since thelight source electrode 47 is electrically connected to the light sourcesupporting substrate 230, the potential of the light source supportingsubstrate 230 can be adjusted to the ground potential, for example,through an electrode 247.

Each of the light source electrodes 47, 48 can be constructed by a layerof Au, Cu, or the like having a thickness of about 1 to 3 μm formed byvacuum vapor deposition, sputtering, or the like, for example, on afoundation layer having a thickness of about 10 nm made of Ta, Ti, orthe like, for example.

The laser diode 40 is electrically connected onto the light sourceelectrode 47 through a solder layer 42 (see FIG. 5) made of a conductivesolder material such as Au—Sn. Here, the laser diode 40 is arranged withrespect to the light source electrode 47 so as to cover only a partthereof.

As shown in FIG. 3, one of leads constituting the wiring member 203 iselectrically connected to the electrode 247, while the electrode 247 isconnected to the light source electrode 47 of the light source unit 23through a reflow solder piece 252. Another lead is electricallyconnected to an electrode 248, while the electrode 248 is connected tothe light source electrode 48 of the light source unit 23 through areflow solder piece 252. Therefore, the laser diode 40 emits light whena driving current is supplied between the electrodes 247, 248.

For forming the reflow solder pieces 250, 252, a method known as solderbonding may be used. Specifically, molten solder balls are bonded to apair of electrodes by ultrasonic waves or the like and then heated by alaser or the like, so as to reflow, thereby bonding the electrodes toeach other with the reflow solder piece 250. Examples of soldermaterials include Au, Sn, Pb and their alloys, though not restricted inparticular.

FIG. 7 is a perspective view of the laser diode 40.

The laser diode 40 may have the same structure as one typically used foroptical disk storage. For example, the laser diode 40 has a structure inwhich an n-electrode 40 a, an n-GaAs substrate 40 b, an n-InGaAlPcladding layer 40 c, a first InGaAlP guide layer 40 d, an active layer40 e made of a multiple quantum well (InGaP/InGaAlP) or the like, asecond InGaAlP guide layer 40 f, a p-InGaAlP cladding layer 40 g, an*n-GaAs current blocking layer 40 h, a p-GaAs contact layer 40 i, and ap-electrode 40 j are successively laminated. Reflective films 50, 51made of SiO₂, Al₂O₃, or the like for pumping oscillations by totalreflection are formed in front and rear of a cleavage surface of themultilayer structure. A light exit end 400 from which the laser light isemitted is provided with an opening at a position corresponding to theactive layer 40 e in one reflective film 50. When a voltage is appliedto thus constructed laser diode 40 in the thickness direction, the laserlight is emitted from the light exit end 400.

As regards the wavelength λ_(L) of laser light to be emitted, a laserdiode adapted to emit laser light having the appropriate wavelengthλ_(L) is selected in view of the form and metal material of thenear-field-light-generating part 36 and the refractive index n of thematerial constituting the waveguide 35 as mentioned above.

As mentioned above, the laser diode 40 has a width (W40) of about 200 to350 μm, a length (or depth L40) of 250 to 600 μm, and a thickness (T40)of about 60 to 200 μm, for example. Here, the width W40 of the laserdiode 40 can be reduced to about 100 μm, for example, while its lowerlimit is the distance between the opposing ends of the current blockinglayer 40 h. However, the length of the laser diode 40 is related to thecurrent density and cannot be made so small. In any case, it will bepreferred if the laser diode 40 secures a considerable size takingaccount of handling at the time of mounting.

For driving the laser diode 40, a power supply in the hard disk drivecan be used. In practice, the hard disk drive is typically equipped witha power supply of about 2 V, for example, whose voltage is high enoughfor laser oscillations. The power consumption of the laser diode 40 isabout several tens of mW and thus can sufficiently be covered by thepower supply in the hard disk drive.

The n-electrode 40 a of the laser diode 40 is secured to the lightsource electrode 47 by the solder layer 42 (see FIG. 4) made of AuSn orthe like. Here, the laser diode 40 is secured to the light sourcesupporting substrate 230 such that the light exit end (light exitsurface) 400 of the laser diode 40 faces down (in the −Z direction) inFIG. 4, i.e., the light exit end 400 is parallel to the bonding surface2300, whereby the light exit end 400 can oppose the light entrancesurface 354 of the waveguide 35 in the slider 22. For securing the laserdiode 40 in practice, for example, a vapor deposition film of an AuSnalloy having a thickness of about 0.7 to 1 μm is formed on the surfaceof the light source electrode 47, and the laser diode 40 is mountedthereon and then secured thereto by heating to about 200 to 300° C. witha hot plate or the like under a hot air blower.

The p-electrode 40 j of the laser diode 40 is electrically connected tothe light source electrode 48 by a bonding wire. Without bonding wires,the laser diode 40 may be provided with a step, so as to reduce thedistance between the light source electrode 48 and the p-electrode 40 jof the laser diode 40, and they may be electrically connected to eachother with solder of AuSn or the like. The light source electrode 47 maybe connected to the p-electrode 40 j instead of the n-electrode 40 a. Inthis case, the n-electrode 40 a is connected to the light sourceelectrode 48 by a bonding wire or the like.

When soldering with the above-mentioned AuSn alloy, the light sourceunit is heated to a high temperature around 300° C., for example. Thelight source unit 23 is manufactured separately from the slider 22 inthis embodiment, whereby the magnetic head part within the slider is notadversely affected by the high temperature. Also, since the magnetichead part 32 and the light source unit 23 are separated from each other,the magnetic head and the state of mounting the light diode in the lightsource unit can be inspected separately from each other, whereby thetotal yield can be improved by combining nondefective products together.

The back face 2201 of the slider 22 and the bonding surface 2300 of thelight source unit 23 are bonded to each other by an adhesive layer 44(see FIG. 5) such as UV-curable adhesive, for example, while the lightexit end 400 of the laser diode 40 is arranged so as to oppose the lightentrance surface 354 of the waveguide 35.

The structures of the laser diode 40 and light source electrodes are notlimited to those in the above-mentioned embodiment as a matter ofcourse. For example, the laser diode 40 may have a different structureusing other semiconductor materials such as those based on GaAlAs. Otherbrazing materials can be used for soldering the laser diode 40 toelectrodes. The laser diode 40 may be formed by epitaxially growing asemiconductor material directly on a unit substrate.

The slider 22 and light source unit 23 may have any sizes. For example,the slider 22 may be a so-called femto slider having a width in thetrack width direction of 700 μm, a length (depth) of 850 μm, and athickness of 230 μm. The light source unit 23 may have substantially thesame width and length as those of the slider in this case. In practice,a conventionally employed laser diode typically has a width of about 250μm, a length (depth) of about 350 μm, and a thickness of about 65 μm,for example. The laser diode 40 having such a size can fully be mountedon a side face of the light source supporting substrate 230 having sucha size, for example. The bottom face of the light source supportingsubstrate 230 may be provided with a groove, within which the laserdiode 40 can be placed.

For example, a spot of a far-field pattern of laser light having reachedthe light entrance surface 354 of the waveguide 35 may have a diameterin the track width direction of about 0.5 to 1.0 μm, for example, and adiameter orthogonal thereto of about 1 to 5 μm, for example. Preferably,in conformity thereto, the waveguide 35 receiving the laser light has athickness T35 of about 2 to 10 μm, for example, which is greater thanthe spot, and a width (W35) in the track width direction of about 1 to200 μm, for example.

Operations

Operations of the thermally assisted magnetic head 21 in accordance withthis embodiment will now be explained.

At the time of a writing or recording action, the thin-film magnetichead 21 hydrodynamically floats by a predetermined flying height abovethe surface of the rotating magnetic disk (medium) 10. Here, the ends ofthe MR device 33 and electromagnetic coil device 34 on themedium-opposing surface S side oppose the magnetic disk 10 with a minutespacing therefrom, so as to effect reading and writing by sensing andapplying a data signal magnetic field, respectively.

When writing a data signal, the laser light propagated from the lightsource unit 23 through the optical waveguide 35 reaches thenear-field-light-generating part 36, whereby near-field light isgenerated by the near-field-light-generating part 36. This raises thetemperature in a predetermined recording area of the magnetic recordingmedium opposing the medium-opposing surface, thereby temporarilylowering the coercivity of the recording area. Therefore, when theelectromagnetic coil device 34 is energized during this coercivitydecreasing period, so as to generate a writing magnetic field,information can be written in the recording area.

When writing is performed on the magnetic disk having a high coercivityby the thin-film magnetic head for perpendicular magnetic recordingwhile employing the thermally assisted magnetic recording scheme, arecording density of 1 Tbits/inch² class, for example, can be achievedby extremely finely dividing recording bits.

The laser light propagating in a direction parallel to the layer surfaceof the waveguide 35 can be made incident on the light entrance surface(end face) 354 of the waveguide 35 in the slider 22 by using the lightsource unit 23 in this embodiment. Namely, laser light having anappropriate size and direction can reliably be supplied in the thermallyassisted magnetic head 21 constructed such that the integration surface2202 and the medium-opposing surface S are perpendicular to each other.This makes it possible to realize thermally assisted magnetic recordingwith a high heating efficiency in the recording layer of the magneticdisk.

In this embodiment, the device electrodes 371 to 376 provided in theslider 22 so as to supply voltages to devices such as theelectromagnetic coil device 34 and MR device 33 in the slider 22 areexposed at the surface 32 a of the slider 22 on the side opposite fromthe medium-opposing surface S without being covered with the lightsource unit 23, so as to be electrically connected to the electrodes ofthe suspension 20 through the reflow solder pieces 250 and the leads 471to 476 exposed at the side face 411 of the light source unit withoutbonding wires. This can reduce failures caused by the bonding wires.

Also, the end parts 471 b to 476 b of the leads 471 to 476 on the sideopposite from the slider 22 are exposed at the surface 411 of theinsulating layer 41. This makes it easier to connect the suspension 20to the leads 471 to 476.

Further, the intermediate parts 471 c to 476 c of the leads 471 to 476are covered with the insulating layer 41, and the light sourceelectrodes 47, 48 are arranged so as to cover the intermediate parts 471c to 476 c while interposing the insulating layer 41 therebetween. Sincethe laser diode 40, leads 471 to 476, and light source electrodes 47, 48are formed on the same side face 2302 of the light source supportingsubstrate 230, they are easy to manufacture. Since the light sourceelectrodes 47, 48 overpass the leads 471 to 476 while being electricallyinsulated therefrom, the width and length of the light source electrodes47, 48 can be made greater while effectively utilizing the area of oneside face 2302 of the light source supporting substrate 230. This makesit easy to electrically connect the laser diode 40 and the light sourceelectrode 47 to each other and form the light source electrode 47 with apart not covered with the laser diode 40, and a light emission test forthe laser diode 40 source and the like can favorably be performed bybringing a voltage applying probe or the like into contact with thisuncovered part and the light source electrode 48 having a large area.

Second Embodiment

The second embodiment of the present invention will now be explainedwith reference to FIG. 8. The second embodiment is the same as the firstembodiment except for the outermost device electrodes 371, 374 in thetrack width direction of the slider 22, which will solely be explained.

In this embodiment, the device electrodes 371, 374 are also exposed atsurfaces 38 b, 38 c in the track width direction of the slider 22, i.e.,side faces of the medium-opposing surface S, respectively. In the endparts 471 a, 474 a on the slider side of the leads 471, 474, thesurfaces opposing the slider are also exposed, while the slider-opposingsurfaces of the end parts 471 a, 474 a of the leads 471, 474 areelectrically connected to side faces of the device electrodes 371, 374by reflow solder pieces 250, respectively. This embodiment can alsoreduce bonding wires.

The present invention can be modified in various ways without beingrestricted to the above-mentioned embodiments

For example, the light source is not limited to the laser diode, but canbe embodied by other light-emitting devices such as LED.

Though the leads 471 to 476 are connected to the electrodes in thesuspension 20 with the reflow solder pieces 252 on the side face 411 ofthe light source unit 23 in the above-mentioned embodiments, they may beelectrically connected to the suspension 20 by reflow solder or the likeon the surfaces of the leads 471 to 476 on the side opposite from theslider 22, i.e., the surfaces opposing the slider 22.

When the side face 411 of the light source unit 23 has a sufficientlylarge track width and the like, the light source electrodes 47, 48 arenot required to overpass the intermediate parts 471 c to 476 c of theleads 471 to 476. In this case, the leads 471 to 476 may be arranged onboth end sides in the track width direction, while the light sourceelectrodes 47, 48 may be provided at the center part in the track widthdirection. Here, the intermediate parts 471 c to 476 c may also beexposed at the surface.

Though all the devices such as the electromagnetic coil device 34 and MRdevice 33 are connected to the electrodes in the suspension 20 throughthe device electrodes 371 to 376, reflow solder pieces 250, and leads471 to 476 without wire bonding in the above-mentioned embodiments, thepresent invention can be embodied if only one of the devices employs theconnecting method mentioned above.

The electromagnetic coil device 34 may be one for longitudinal magneticrecording. In this case, lower and upper magnetic pole layers areprovided instead of the main magnetic pole layer 340 and auxiliarymagnetic pole layer 344, and a writing gap layer is held between the endparts on the medium-opposing surface S side of the lower and uppermagnetic pole layers. Writing is effected by a leakage magnetic fieldfrom the position of the writing gap layer.

The near-field-generating part may employ a so-called “bowtie” structurein which a pair of triangular or trapezoidal plates are arranged suchthat their vertexes or shorter sides oppose each other while beingseparated by a predetermined distance therebetween. Thenear-field-generating part may have a minute opening instead of theplate. The laser light may be allowed to directly impinge on therecording medium without providing the near-field-generating part.

Though provided by one layer in FIG. 4 and the like, the coil layer 342may be constituted by two or more layers or a helical coil.

The heat insulating layer 230 a may be formed on the back face 2201 ofthe slider substrate 220 or totally omitted.

For bonding the light source unit 23 and slider 22 to each other,adhesives other than the UV-curable adhesive, e.g., the solder layermade of AuSn or the like used for bonding the laser diode 40 and lightsource electrode 47 to each other, may also be employed.

Though employed as a linear waveguide in the above-mentioned embodiment,the waveguide 35 may be a parabolic waveguide whose outer form withinthe YZ plane exhibits a parabola with the near-field-generating partarranged at its focal position, or have an elliptical outer form or thelike within the YZ plane or a taper form in which the leading end closerto the medium is tapered. The hard disk drive equipped with theabove-mentioned thermally assisted magnetic head and HGA can fullyprevent writing errors from occurring because of insufficiently heatingthe recording medium during writing actions, while fully keeping sideerasure from occurring.

All the foregoing embodiments show the present invention illustrativelybut not restrictively, whereby the present invention can be carried outin various other modified and altered modes. Therefore, the scope of thepresent invention is defined only by the claims and their equivalents.

1. A thermally assisted magnetic head comprising a slider having amedium-opposing surface, and a light source unit arranged on a surfaceof the slider on the side opposite from the medium-opposing surface;wherein the slider has a slider substrate, an electromagnetictransducer, a waveguide for receiving light from the surface oppositefrom the medium-opposing surface and guiding the light to themedium-opposing surface side, and a device electrode electricallyconnected to the electromagnetic transducer; wherein the light sourceunit has a light source supporting substrate secured with respect to theslider substrate, a light source secured with respect to the lightsource supporting substrate so as to be able to supply the light to thewaveguide, and a lead extending from the slider side to the sideopposite from the slider and having both end parts exposed at a surfaceof the light source unit; wherein the device electrode of the slider isexposed at the surface of the slider on the side opposite from themedium-opposing surface without being covered with the light sourceunit, or exposed at a side face of the medium-opposing surface of theslider; and wherein an end part on the slider side of the lead of thelight source unit is soldered to the device electrode of the slider. 2.A thermally assisted magnetic head according to claim 1, wherein bothend parts of the lead of the light source unit are exposed at the sameside face of the light source unit, while the device electrode of theslider is exposed at the surface of the slider on the side opposite fromthe medium-opposing surface without being covered with the light sourceunit.
 3. A thermally assisted magnetic head according to claim 2,wherein the light source and lead are arranged on the same side face ofthe light source supporting substrate; wherein an intermediate part ofthe lead between the end part on the slider side and the end part on theside opposite from the slider is covered with an insulating layerwithout being exposed at the surface of the light source unit; wherein alight source electrode is provided on the insulating layer; and whereinthe light source is arranged on the light source electrode.
 4. A headgimbal assembly comprising: the thermally assisted magnetic headaccording to claim 1; and a suspension for supporting the thermallyassisted magnetic head.
 5. A hard disk drive comprising: the head gimbalassembly according to claim 4; and a magnetic recording medium.
 6. Athermally assisted magnetic head comprising a slider having amedium-opposing surface, and a light source unit arranged on a surfaceof the slider on the side opposite from the medium-opposing surface;wherein the slider has a slider substrate, an electromagnetictransducer, an auxiliary device to be applied with a voltage, awaveguide for receiving light from the surface opposite from themedium-opposing surface and guiding the light to the medium-opposingsurface side, and a device electrode electrically connected to theauxiliary device; wherein the light source unit has a light sourcesupporting substrate secured with respect to the slider substrate, alight source secured with respect to the light source supportingsubstrate so as to be able to supply the light to the waveguide, and alead extending from the slider side to the side opposite from the sliderand having both end parts exposed at a surface of the light source unit;wherein the device electrode of the slider is exposed at the surface ofthe slider on the side opposite from the medium-opposing surface withoutbeing covered with the light source unit, or exposed at a side face ofthe medium-opposing surface of the slider; and wherein an end part onthe slider side of the lead of the light source unit is soldered to thedevice electrode of the slider.
 7. A thermally assisted magnetic headaccording to claim 6, wherein both end parts of the lead of the lightsource unit are exposed at the same side face of the light source unit,while the device electrode of the slider is exposed at the surface ofthe slider on the side opposite from the medium-opposing surface withoutbeing covered with the light source unit.
 8. A thermally assistedmagnetic head according to claim 7, wherein the light source and leadare arranged on the same side face of the light source supportingsubstrate; wherein an intermediate part of the lead between the end parton the slider side and the end part on the side opposite from the slideris covered with an insulating layer without being exposed at the surfaceof the light source unit; wherein a light source electrode is providedon the insulating layer; and wherein the light source is arranged on thelight source electrode.
 9. A head gimbal assembly comprising: thethermally assisted magnetic head according to claim 6; and a suspensionfor supporting the thermally assisted magnetic head.
 10. A hard diskdrive comprising: the head gimbal assembly according to claim 9; and amagnetic recording medium.